Warning, file /frameworks/kdelibs4support/src/kdeui/kfadewidgeteffect.cpp was not indexed or was modified since last indexation (in which case cross-reference links may be missing, inaccurate or erroneous).

 /*  This file is part of the KDE project
     Copyright (C) 2008 Matthias Kretz <kretz@kde.org>
     Copyright (C) 2008 Rafael Fernández López <ereslibre@kde.org>
 
     This program is free software; you can redistribute it and/or
     modify it under the terms of the GNU Library General Public
     License as published by the Free Software Foundation; either
     version 2 of the License, or (at your option) version 3.
 
     This library is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     Library General Public License for more details.
 
     You should have received a copy of the GNU Library General Public License
     along with this library; see the file COPYING.LIB.  If not, write to
     the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
     Boston, MA 02110-1301, USA.
 
 */
 
 #include "kfadewidgeteffect.h"
 #include "kfadewidgeteffect_p.h"
 
 #include <QEvent>
 #include <QPaintEngine>
 #include <QPainter>
 #include <QStyle>
 
 KFadeWidgetEffectPrivate::KFadeWidgetEffectPrivate(QWidget *_destWidget)
     : destWidget(_destWidget), disabled(false)
 {
 }
 
 // Code from KFileItemDelegate (Author: Frederik Höglund)
 // Fast transitions. Read:
 // http://techbase.kde.org/Development/Tutorials/Graphics/Performance
 // for further information on why not use setOpacity.
 QPixmap KFadeWidgetEffectPrivate::transition(const QPixmap &from, const QPixmap &to, qreal amount) const
 {
     const int value = int(0xff * amount);
 
     if (value == 0) {
         return from;
     }
 
     if (value == 1) {
         return to;
     }
 
     QColor color;
     color.setAlphaF(amount);
 
     // If the native paint engine supports Porter/Duff compositing and CompositionMode_Plus
     if (from.paintEngine()->hasFeature(QPaintEngine::PorterDuff) &&
             from.paintEngine()->hasFeature(QPaintEngine::BlendModes)) {
         QPixmap under = from;
         QPixmap over  = to;
 
         QPainter p;
         p.begin(&over);
         p.setCompositionMode(QPainter::CompositionMode_DestinationIn);
         p.fillRect(over.rect(), color);
         p.end();
 
         p.begin(&under);
         p.setCompositionMode(QPainter::CompositionMode_DestinationOut);
         p.fillRect(under.rect(), color);
         p.setCompositionMode(QPainter::CompositionMode_Plus);
         p.drawPixmap(0, 0, over);
         p.end();
 
         return under;
     } else {
         // Fall back to using QRasterPaintEngine to do the transition.
         QImage under = from.toImage();
         QImage over  = to.toImage();
 
         QPainter p;
         p.begin(&over);
         p.setCompositionMode(QPainter::CompositionMode_DestinationIn);
         p.fillRect(over.rect(), color);
         p.end();
 
         p.begin(&under);
         p.setCompositionMode(QPainter::CompositionMode_DestinationOut);
         p.fillRect(under.rect(), color);
         p.setCompositionMode(QPainter::CompositionMode_Plus);
         p.drawImage(0, 0, over);
         p.end();
 
         return QPixmap::fromImage(under);
     }
 }
 
 KFadeWidgetEffect::KFadeWidgetEffect(QWidget *destWidget)
     : QWidget(destWidget ? destWidget->parentWidget() : nullptr),
       d_ptr(new KFadeWidgetEffectPrivate(destWidget))
 {
     Q_D(KFadeWidgetEffect);
     d->q_ptr = this;
     Q_ASSERT(destWidget && destWidget->parentWidget());
     if (!destWidget || !destWidget->parentWidget() || !destWidget->isVisible() ||
             !style()->styleHint(QStyle::SH_Widget_Animate, nullptr, this)) {
         d->disabled = true;
         hide();
         return;
     }
     setGeometry(QRect(destWidget->mapTo(parentWidget(), QPoint(0, 0)), destWidget->size()));
     d->oldPixmap = destWidget->grab();
     d->timeLine.setFrameRange(0, 255);
     d->timeLine.setCurveShape(QTimeLine::EaseOutCurve);
     connect(&d->timeLine, SIGNAL(finished()), SLOT(finished()));
     connect(&d->timeLine, SIGNAL(frameChanged(int)), SLOT(repaint()));
     show();
 }
 
 KFadeWidgetEffect::~KFadeWidgetEffect()
 {
     delete d_ptr;
 }
 
 void KFadeWidgetEffectPrivate::finished()
 {
     Q_Q(KFadeWidgetEffect);
     destWidget->setUpdatesEnabled(false);
     q->hide();
     q->deleteLater();
     destWidget->setUpdatesEnabled(true);
 }
 
 void KFadeWidgetEffect::start(int duration)
 {
     Q_D(KFadeWidgetEffect);
     if (d->disabled) {
         deleteLater();
         return;
     }
     d->newPixmap = d->destWidget->grab();
     d->timeLine.setDuration(duration);
     d->timeLine.start();
 }
 
 void KFadeWidgetEffect::paintEvent(QPaintEvent *)
 {
     Q_D(KFadeWidgetEffect);
     QPainter p(this);
     p.drawPixmap(rect(), d->transition(d->oldPixmap, d->newPixmap, d->timeLine.currentValue()));
     p.end();
 }
 
 #include "moc_kfadewidgeteffect.cpp"